are there big conventions for all three professions? when you write a history thesis or dissertation, do you anxiously watch the news for new archeology finds that might invalidate your theories? When do theories graduate into generally accepted knowledge?
Edit: Thank you, this is fascinating stuff. Big thanks to mods for an awesome subreddit.
I am a recent graduate with degrees in both History (Early Modern) and Anthropology (Archaeology) and I think I can speak somewhat to this question.
Historians, as their name suggests, are primarily concerned with "historical" sources that being sources that are written records of past events. When we say "pre-historical" what we mean is a period before records were kept. An anthropologist, and archaeologist in particular, is concerned primarily with physical culture. Whether it is artwork, architecture, or any other physical manifestation of a society. Effectively the role of an archaeologist is to collect, catalogue, maintain and interpret physical culture vis-a-vis its provenance.
Both disciplines rely upon eachother to produce a more nuanced, and accurate, view of historical societies, but generally are held apart. Many historians prefer to work solely with texts and have no experience on archaeological digs. Similarly many archaeologists deal exclusively in the analytically and taxonomic nature of their study and pay little attention to the context of their studies.
There is an intersection of these two fields called "Historical Archaeology" which informs the search and interpretation of physical culture with known written sources. A perfect example of this discipline would be the recent exhumation of, the now confirmed, body of Richard III. The dig site was chosen by interpreting numerous sources that pointed to a particular chapel as the burial site of the King. In turn they dug a number of slit trenches around the known foundations of this chapel and were able to determine the likely area of the graveyard. This was all accomplished through the integration of both disciplines.
As to you question about conflicting theories and interpretations. Yes there are a tremendous number of conflicts within history and archaeology alike. Competing methodologies often build camps around particular historical events and fight over interpretation and semantics. This should come with very little surprise given the nature of all academia. Unfortunately academic disagreements are typically so esoteric and specific that they can be easily ignored by the lay-person.
One glaring example is the growing movement within the US history community to no longer refer to the "American Revolution" as a revolution at all. The foundation for this argument is based upon what constitutes a revolution, the technical definition among historians, and how the American revolution could possibly be considered one. There is a growing consensus among modern historians that the American "revolution" was more a civil war or uprising because it was effectively maintaining a status quo within the colonies, but that is neither here nor there.
What is important is that consensus within the historical community is not always what is accepted knowledge. Accepted knowledge, and this is coming from my anthropology side, is what a society chooses to believe about itself and others. Often times it is not accurate, or even factual, and when we discuss history our Accepted Knowledge is rarely correct. It takes years of concerted effort by historians to steer the massive weight of public consciousness away from inaccurate interpretations and towards more factual, or atleast accepted, conceptions of the past.
Some good news is that historians, anthropologists, and archaeologists are cooperating more and more. As interdepartmental study is becoming a major force in education I think we can expect more students to graduate with a much greater breadth of knowledge.
In the United States (I don't know about elsewhere) Archaeology is considered a field of Anthropology. Furthermore, Anthropology is broken into the other disciplines of Biological (Physical) Anthropology, Cultural Anthropology, and Linguistics.
Beyond that, even within a sub-discipline like cultural anthropology, there are many disagreements on how research should be conducted and the paradigms used to interpret data.
I can't speak to historians (so maybe I shouldn't even be answering here) but, yes, there are disagreements, not just among the three groups you listed, but within them as well.
If I could recommend a classic article on this subject, from ethno-historian (and trained anthropologist) Jan Vansina:
Vansina, Jan, “Historians, Are Archaeologists Your Siblings”, History in Africa, 22 (1995), 369-408.
After Vansina’s article was posted online to H-Africa, the archaeologist [Robert Bradshaw responded] (http://www.h-net.msu.edu/~africa/africaforum/Roderick J.shaw.html)
There are constant disagreements about historical facts and that's part of the process. Historians work with imperfect tools in a field where its near impossible to 'prove' that something happened. We have to look at the primary sources, see if we can figure out what the facts are and argue those facts to peers in a comprehensive and articulate manner. A good historian will do all that and then try to explain the broader context and importance.
I don't know if there are conventions but scholarly discussion like what I think you're alluding to occurs in publications and research journals. There's always a steady flow of theses (thesises?) that get reviewed by peers (AKA peer review). If a theory holds up to scholarly scrutiny then it becomes accepted. When a theory's argument grows stronger as new evidence emerges over time then it generally graduates into common knowledge.
And as for your second question I haven't written a historical thesis so I can't say what it's like to have your arguments invalidated. I'm sure there's disappointment but if a historian can see the bigger picture of their field they'd probably be accepting of it.